Background: PSSA framework recap and Papahānaumokuākea placement
A Particularly Sensitive Sea Area is an area recognised by the International Maritime Organization as needing special protection through IMO action because of its ecological, socio-economic or scientific significance and its vulnerability to damage from international shipping. The operative instrument is IMO Assembly Resolution A.982(24) of 1 December 2005, the Revised PSSA Guidelines. A coastal state proposes the designation to the Marine Environment Protection Committee (MEPC) under three criterion families (ecological, social-cultural-economic, scientific-educational), paired with Associated Protective Measures (APMs) drawn from existing IMO instruments. The architecture was first applied to the Great Barrier Reef PSSA in 1990, then to the Wadden Sea PSSA in 2002, the Western European Waters PSSA in 2004, the Galapagos PSSA and the Baltic Sea PSSA in 2005, and the Tubbataha Reefs PSSA in 2017.
The Papahānaumokuākea PSSA, designated by Resolution MEPC.171(57) at the 57th session of the MEPC on 4 April 2008, is the eleventh PSSA globally and the second in United States waters after the Florida Keys PSSA of 2002. The placement is distinctive on three grounds. First, the PSSA covers an entire emergent island chain, atolls and shoals stretching across roughly 1,931 km of central North Pacific Ocean, anchored by the inhabited Midway Atoll and uninhabited Kure, Pearl and Hermes, Lisianski, Laysan, Maro Reef, Gardner Pinnacles, French Frigate Shoals, Necker (Mokumanamana) and Nihoa. Second, the PSSA falls within an exclusive United States Exclusive Economic Zone, allowing the federal government to combine domestic legal authority (the Antiquities Act of 1906) with international IMO instruments. Third, the PSSA is integrated with native Hawaiian cultural-ancestral governance through the Office of Hawaiian Affairs and a dedicated cultural working group, distinguishing it from purely ecological PSSAs.
Vulnerability to international shipping is principally transit-driven: the Northwestern Hawaiian Islands lie astride the Trans-Pacific great-circle route between the United States West Coast and Asia, with approximately 12,000 ships per year transiting the wider Hawaiian-archipelago corridor. Cargo casualties, oil pollution from bunker fuel, ballast and hull-borne invasive species, and anchor damage to coral are the principal vectors addressed by the IMO ATBA and the supporting Pacific Mariners Reporting Schedule.
Papahānaumokuākea Marine National Monument ecological value
The Papahānaumokuākea Marine National Monument spans approximately 939,000 km² of central North Pacific Ocean from the Hawaii main-island chain north-westward to Kure Atoll and the international date-line region. The Monument encompasses ten islands and atolls plus extensive submerged seamounts and shallow banks, descending from emergent reef platform to abyssal seafloor below 4,000 metres. The bathymetry combines the volcanic seamount chain extending the Hawaiian-Emperor hotspot trail with shallow coral atolls that subsided over millions of years, producing one of the most geologically and biologically complete marine ecosystem chronosequences on Earth.
The biological inventory is exceptional both for diversity and for endemism. Approximately 7,000 marine species are documented, of which roughly 1,750 are endemic to the Hawaiian archipelago, an endemism rate around 25 percent and the highest documented for any tropical marine region. Endemic flagship species include the Hawaiian monk seal (Neomonachus schauinslandi), one of the world’’s most endangered pinnipeds with approximately 1,600 individuals concentrated in the Northwestern Hawaiian Islands; the Laysan duck (Anas laysanensis), the rarest waterfowl in the Northern Hemisphere; the Laysan finch (Telespiza cantans); the Nihoa millerbird (Acrocephalus familiaris); and approximately 25 percent of all Hawaiian endemic reef fish species.
The Monument supports approximately 14 million seabirds across 22 species, including 99 percent of the world’’s Laysan albatross (Phoebastria immutabilis), 98 percent of the world’’s black-footed albatross (Phoebastria nigripes), and the entire Northern Hemisphere population of the short-tailed albatross (Phoebastria albatrus) outside Japan’’s Torishima colony. Cetacean populations include resident Hawaiian populations of false killer whales (Pseudorca crassidens), short-finned pilot whales (Globicephala macrorhynchus), pantropical spotted dolphins (Stenella attenuata) and seasonal humpback whales (Megaptera novaeangliae) on the winter calving migration from Alaskan feeding grounds.
The marine turtle inventory comprises green turtles (Chelonia mydas) with documented French Frigate Shoals nesting (the principal Hawaiian nesting site), hawksbill turtles (Eretmochelys imbricata), olive ridley (Lepidochelys olivacea) and leatherback (Dermochelys coriacea) seasonal foragers. The shark fauna includes Galapagos, sandbar, tiger, scalloped hammerhead, whitetip and grey reef sharks across the atoll system.
The reef structures of Pearl and Hermes, French Frigate Shoals, Maro Reef and Lisianski host approximately 60 percent of all Hawaiian reef coral species, with several species endemic to the Northwestern Hawaiian Islands. The deep banks and seamounts at Cross, Salmon, Bank 66 and Pioneer support black coral (Antipatharia) and gold coral (Kulamanamana haumeaae) communities of high commercial fisheries interest.
UNESCO World Heritage 2010: first US mixed natural and cultural marine site
Papahānaumokuākea was inscribed on the UNESCO World Heritage List on 30 July 2010 by the World Heritage Committee at its 34th session in Brasilia. The inscription was the first mixed natural and cultural World Heritage property in United States territory and remains, alongside the 2017 expansion under Resolution MEPC.297(72), one of the largest UNESCO World Heritage marine sites globally.
The natural-criteria inscription rests on criteria (viii), (ix) and (x). Criterion (viii) recognises the geological story of the Hawaiian-Emperor hotspot chain, where Papahānaumokuākea preserves an in-situ chronosequence from young volcanic islands to subsided guyots stretching across approximately 30 million years of seafloor history. Criterion (ix) cites on-going biological and ecological processes of an isolated open-ocean ecosystem, and the high endemism arising from extreme isolation. Criterion (x) cites natural habitats of biodiversity significance, including monk seals, sea turtles and seabirds.
The cultural-criteria inscription rests on criteria (iii) and (vi). Criterion (iii) recognises the surviving cultural traditions of the Kanaka Maoli (Native Hawaiian) people centred on Nihoa and Mokumanamana (Necker Island), where archaeological remains include 88 stone shrines (heiau), agricultural terraces and burial sites dating from approximately AD 1000 to AD 1700 and tied to the navigation, religious and astronomical traditions of pre-contact Hawaii. Criterion (vi) recognises the spiritual and ancestral significance of Papahānaumokuākea in living Hawaiian cosmology, where the chain of islands is understood as the realm of the gods and ancestors and is governed by the kapu system regulating access, fishing, harvest and ceremony.
The World Heritage statement notes that Papahānaumokuākea is the only marine UNESCO property where ancestral indigenous cultural traditions are formally integrated with natural-resource governance through statutory co-management. The IUCN Outlook Assessment for Papahānaumokuākea classifies the conservation outlook as good, attributing the favourable assessment in part to the integrated co-management framework and the operational PSSA architecture limiting shipping risk.
2006 Proclamation 8031 (G.W. Bush)
President George W. Bush established the Northwestern Hawaiian Islands Marine National Monument by Proclamation 8031 of 15 June 2006, designating approximately 360,000 km² of central North Pacific Ocean and superseding earlier overlapping designations including the Hawaiian Islands National Wildlife Refuge of 1909, the Midway Atoll National Wildlife Refuge of 1988 and the Northwestern Hawaiian Islands Coral Reef Ecosystem Reserve established by Executive Order 13178 of 2000. The proclamation invoked the Antiquities Act of 1906 (54 U.S.C. § 320301), authorising the President to declare federal-land objects of historic or scientific interest to be national monuments. Proclamation 8031 was renamed Papahānaumokuākea Marine National Monument by Proclamation 8112 of 6 March 2007, formally adopting the Native Hawaiian name proposed by the Office of Hawaiian Affairs.
The 2006 boundary extended approximately 80 km on either side of the Northwestern Hawaiian Islands from Nihoa Island in the south-east to Kure Atoll in the north-west, encompassing all federal waters around the chain plus the seabed and subsoil. The proclamation prohibited commercial fishing on a five-year phase-out, anchoring on living coral, and unpermitted vessel transits through the Monument core, while preserving native Hawaiian subsistence and cultural practices. Co-management was assigned to the Department of Commerce (NOAA), the Department of the Interior (USFWS) and the State of Hawaii Department of Land and Natural Resources, formalised through a Memorandum of Agreement signed in 2007.
The 2006 proclamation was the largest marine protected area in the world at the time of designation. It was the doctrinal precursor for the subsequent expansion of the Pacific Remote Islands Marine National Monument in 2014 (also under the Antiquities Act) and for the wider Pacific Marine Monument programme of the Obama presidency.
2016 Proclamation 9478 expansion (Obama) to ~939,000 km²
President Barack Obama expanded Papahānaumokuākea by Proclamation 9478 of 26 August 2016, increasing the Monument from approximately 360,000 km² to ~939,000 km², an expansion of approximately 579,000 km² that extended the boundary from 80 km on either side of the islands to the full United States Exclusive Economic Zone (200 nautical miles) around the Northwestern Hawaiian Islands. The expansion was developed in coordination with the Office of Hawaiian Affairs, the State of Hawaii, NOAA, USFWS, and Native Hawaiian community representatives, and was published in the Federal Register on 1 September 2016.
The 2016 boundary captures the full EEZ envelope around Nihoa, Mokumanamana, French Frigate Shoals, Gardner Pinnacles, Maro Reef, Laysan, Lisianski, Pearl and Hermes, Midway and Kure, plus the deep waters and seamounts between them. The expansion incorporated approximately 100 additional seamounts, several previously unmapped, and habitat for deep-water corals, billfish, tunas and migratory predators including white-tip and oceanic-whitetip shark populations of recovering status.
The proclamation reaffirmed Native Hawaiian cultural-practitioner access for traditional, customary and subsistence harvesting consistent with the kapu system. It expanded the prohibition on commercial fishing across the new 2016 boundary on a five-year phase-out, retained the existing prohibitions on anchoring and unpermitted transits, and extended IMO ATBA observance and Pacific Mariners Reporting Schedule reporting to the new boundary. The Co-Trustee architecture was extended in 2017 to include the Office of Hawaiian Affairs (OHA) as a fourth co-trustee alongside NOAA, USFWS and Hawaii DLNR, the first formal indigenous co-trusteeship of a federal United States marine protected area.
The 2016 expansion makes Papahānaumokuākea, by area, the largest contiguous fully-protected marine area under United States jurisdiction. It is comparable in scale to the Pitcairn Islands Marine Reserve (United Kingdom) and the Ross Sea Region Marine Protected Area (Antarctica) within the Antarctic Special Area framework.
MEPC.171(57) PSSA designation (March 2008)
The Papahānaumokuākea PSSA was designated by Resolution MEPC.171(57) at the 57th session of the Marine Environment Protection Committee on 4 April 2008. The United States proposal was developed by NOAA, the United States Coast Guard, the United States Fish and Wildlife Service, the State of Hawaii Department of Land and Natural Resources and the United States Permanent Mission to the IMO during 2006 and 2007 following the establishment of the original Monument under Proclamation 8031.
The proposal was submitted as MEPC 56/INF.18 in 2007 and discussed at MEPC 56 in July 2007. It was adopted by consensus at MEPC 57 in April 2008 as Resolution MEPC.171(57), with the Associated Protective Measures comprising the area-to-be-avoided and the Pacific Mariners Reporting Schedule both adopted at the same session. The PSSA designation was effective from adoption, with the ATBA entering force on 1 May 2008 following publication on Notice to Mariners and entry into nautical chart updates by the United States Coast Guard, the National Oceanic and Atmospheric Administration nautical-chart office, the United Kingdom Hydrographic Office and other principal hydrographic offices.
The 2008 PSSA covered the original 2006 Monument boundary. Following the 2016 Monument expansion, the United States submitted MEPC 71/INF.21 in 2017 notifying the IMO of the boundary update and the corresponding ATBA expansion. The IMO accepted the boundary update administratively, and the Pacific Mariners Reporting Schedule and ATBA were updated in nautical chart releases through 2017 and 2018.
APM 1: IMO-mandated ATBA for ships ≥1,000 GT
The first Associated Protective Measure is an area-to-be-avoided (ATBA) for ships of 1,000 gross tonnage and above, established under SOLAS Regulation V/10 and the Ships’’ Routeing publication. The ATBA covers the full Monument boundary as updated in 2017, an area of approximately 939,000 km² of central North Pacific. Ships of 1,000 GT and above carrying any cargo are required to remain outside the ATBA except in case of force majeure, vessel or crew safety, or under permit.
The ATBA threshold of 1,000 GT is higher than the Tubbataha Reefs threshold of 150 GT and matches the Galapagos and Great Barrier Reef approach for an area dominated by larger transit traffic rather than coastal shipping. The threshold reflects that the principal external vector is bulk and container traffic on Trans-Pacific routes, since smaller commercial fishing or recreational vessels operating closer to the main islands generally do not enter the Monument boundary.
Implementation is supported by satellite Automatic Identification System (AIS) monitoring through the United States Coast Guard Sector Honolulu and NOAA Office of National Marine Sanctuaries enforcement. Shore-based AIS coverage from Midway Atoll (an inhabited US Fish and Wildlife refuge), French Frigate Shoals (a NOAA research field camp until 2018) and the main Hawaiian Islands provides partial coverage, with satellite AIS bridging gaps. AIS detection of unauthorised entries triggers Coast Guard hailing, vessel-of-interest tracking and, where evidence supports prosecution, civil-penalty proceedings under the Antiquities Act, the National Marine Sanctuaries Act (16 U.S.C. § 1431 et seq.) and Title 50 Code of Federal Regulations Part 404 (the Monument regulations).
APM 2: Pacific Mariners Reporting Schedule
The second Associated Protective Measure is the Pacific Mariners Reporting Schedule (PSSAREP), a mandatory ship-reporting system established under SOLAS Regulation V/11 and adopted at MEPC 57 alongside the PSSA designation. PSSAREP requires ships of 300 gross tonnage and above intending to transit the wider Northwestern Hawaiian Islands corridor to report to the United States Coast Guard at three points: when entering the buffer zone outside the ATBA, on any course alteration toward the ATBA, and on departure from the buffer zone.
Each PSSAREP message conveys vessel name, IMO number, callsign, position, course, speed, destination, cargo type, fuel type and bunker quantity. The data feeds into Coast Guard Sector Honolulu vessel traffic services, NOAA enforcement and inter-agency coordination with US Customs and Border Protection. PSSAREP submissions are transmitted by satellite communications, AIS data link or the equivalent international GMDSS channels.
PSSAREP integrates with the existing Hawaii Vessel Traffic Service for the main Hawaiian Islands and with the wider Pacific Ship Reporting System. The reporting schedule is published in the United States Coast Pilot Volume 7 (Pacific Coast and Hawaii) and in IMO MSC.1/Circ.1224 documenting amended ship reporting systems. Compliance has been generally high: the United States Coast Guard reports approximately 95 percent compliance among 1,000 GT and above transits, with non-compliance largely attributable to unfamiliarity rather than wilful evasion, and addressed through Notice-to-Mariners broadcasts and port-state outreach in the United States West Coast and Asian terminal ports.
APM 3: Anchoring and discharge restrictions
The third Associated Protective Measure prohibits anchoring on coral and prohibits MARPOL discharges within the Monument boundary, going beyond the baseline MARPOL Annex I, IV, V and VI standards applicable globally. The anchoring prohibition covers all vessels entering the Monument by permit, and is supported by mooring-buoy installations at Midway Atoll and French Frigate Shoals for permitted research, native Hawaiian cultural-practice and law-enforcement vessels.
The discharge regime prohibits any operational discharge from vessels within the Monument boundary, including treated sewage, food waste, oil-contaminated bilge water, exhaust gas cleaning system (scrubber) wash water, ballast water, and grey water. Permitted research vessels operating under NOAA, USFWS or university authorisation are required to retain all wastes on board for shore disposal. The regime is closer in scope to the Antarctic Treaty Annex IV sewage and waste prohibitions than to the standard MARPOL Annex IV or Annex V regimes, reflecting the extreme remoteness, the endemic-species sensitivity and the cultural-heritage status of the Monument.
Hull-fouling and ballast-water biosecurity is regulated under the State of Hawaii Hull Fouling Rules (HAR Title 13 Chapter 76) and the United States Coast Guard ballast-water regulations, with additional pre-arrival inspection for permitted research and cultural-practitioner vessels. Invasive-species risk is the principal residual ecological risk vector for the Monument, and biosecurity protocols are tighter for Papahānaumokuākea than for any other United States marine sanctuary or monument.
Co-management: NOAA + USFWS + Hawaii DLNR + OHA
Papahānaumokuākea is governed by a four-party Co-Trustee structure unique among United States marine protected areas. The four Co-Trustees are:
- National Oceanic and Atmospheric Administration (NOAA), lead federal trustee through the Office of National Marine Sanctuaries, responsible for marine-water management, scientific research coordination and IMO PSSA implementation
- United States Fish and Wildlife Service (USFWS), federal trustee responsible for terrestrial and submerged-lands wildlife refuges (Hawaiian Islands National Wildlife Refuge, Midway Atoll National Wildlife Refuge), seabird management and threatened-species protection
- State of Hawaii Department of Land and Natural Resources (DLNR), state trustee responsible for state waters around Nihoa and the inshore zones, fisheries enforcement and the state Marine Life Conservation District network
- Office of Hawaiian Affairs (OHA), native Hawaiian trustee added in 2017 following Proclamation 9478, responsible for Native Hawaiian cultural-practitioner access, traditional and customary uses, and the Native Hawaiian Cultural Working Group
Operational coordination is provided through the Monument Management Board (MMB), which meets monthly with rotating chairs and prepares annual operations plans. Day-to-day administration is housed at the Mokupāpapa Discovery Center in Hilo on Hawaii Island and at NOAA’’s Inouye Regional Center in Honolulu. The Co-Trustees jointly adopt the Monument Management Plan (revised on a five-year cycle, with the most recent revision finalised in 2024 to reflect the post-2017 expansion and post-2020 climate-adaptation programme).
The four-party structure has been cited internationally as a model for indigenous co-trusteeship of marine protected areas, including in the parallel Sea Country IPA (Indigenous Protected Area) framework in Australia, the Haida Gwaii Marine Plan in Canada, and the bicultural management arrangements at the Galapagos PSSA for native Galapagueño communities.
Native Hawaiian Cultural Working Group
The Native Hawaiian Cultural Working Group (NHCWG) was established in 2007 under Proclamation 8112 (the renaming proclamation) as the cultural advisory body for the Monument. The NHCWG is composed of approximately 12 to 15 native Hawaiian cultural practitioners, kūpuna (elders), educators and traditional-knowledge holders, appointed in rotation by OHA in coordination with the Co-Trustees. The NHCWG advises on cultural-resource management, cultural-practitioner access permits, ceremonial protocols at Nihoa and Mokumanamana, archaeological-site protection, language and place-name use, and integration of traditional knowledge into ecosystem management.
The NHCWG developed the Mai Ka Pō Mai management framework, the cultural guidance document adopted in 2021 that translates Hawaiian cosmological understanding of Papahānaumokuākea (the “place of life-giving streams”) into operational management principles. Mai Ka Pō Mai introduces concepts including kuleana (responsibility), mālama (stewardship), and kapu (sacred prohibition) into the management plan, complementing the technical-regulatory provisions inherited from the federal and IMO frameworks.
The cultural-practitioner permit programme allows native Hawaiian practitioners to access Nihoa and Mokumanamana for ceremonial, ancestral, educational and limited-subsistence purposes consistent with the kapu system. Permitted activities include the Mokumanamana Cultural Expedition, conducted approximately every two to three years since 2003, and ongoing ancestral-name and place-name research expeditions.
The NHCWG also coordinates with the Polynesian Voyaging Society for traditional-vessel transits of Papahānaumokuākea by the Hōkūleʻa and Hikianalia voyaging canoes, which transit the Monument under cultural-practitioner authorisation rather than under the standard ATBA framework. The Hōkūleʻa transits are documented as part of the Monument’’s educational mission and the wider Polynesian Voyaging revitalisation of traditional non-instrument navigation across the Pacific.
Relationship to US Caribbean ECA (cross-link to article 41)
The US Caribbean ECA is the MARPOL Annex VI emission control area covering Puerto Rico and the United States Virgin Islands, designated under Resolution MEPC.202(62) in 2011 and entering force on 1 January 2014. The US Caribbean ECA imposes 0.10 percent sulphur and Tier III NOx limits within 50 nautical miles of designated baselines around Puerto Rico, St Thomas, St John and St Croix.
The US Caribbean ECA and Papahānaumokuākea PSSA are complementary federal instruments addressing different vectors. The ECA targets atmospheric emissions of SOx, NOx and particulate matter affecting Caribbean public health and ecosystem chemistry. The PSSA targets routeing, anchoring, discharge and ship reporting affecting Northwestern Hawaiian Islands ecology and cultural heritage. Together with the North American ECA, the two ECAs and the two PSSAs constitute the principal United States special-area architecture for international shipping under MARPOL.
A vessel transiting from Puerto Rico to Honolulu via the Panama Canal would clear the US Caribbean ECA on departure from San Juan, transit Panama, then transit the Pacific to Hawaii, encountering the Papahānaumokuākea ATBA only if routed across the Northwestern Hawaiian Islands corridor. Most Trans-Pacific service from the Panama Canal to Honolulu routes south of the Monument and is therefore unaffected by the ATBA, although it remains subject to PSSAREP reporting in the buffer zone.
Relationship to North American ECA: Hawaii exclusion (cross-link to article 40)
The North American ECA, designated by Resolution MEPC.190(60) in 2010 and entering force on 1 August 2012, covers waters within 200 nautical miles of the United States and Canadian Pacific, Atlantic and Gulf coasts. The North American ECA explicitly excludes the State of Hawaii, the Pacific Remote Islands and the United States Pacific territories of Guam, the Commonwealth of the Northern Mariana Islands, and American Samoa. The Hawaii exclusion was negotiated in 2009 to reflect the limited adjacent shipping density, the absence of major refining infrastructure, and the higher costs of low-sulphur fuel supply in the Hawaiian Islands relative to the United States West Coast.
Papahānaumokuākea, lying north-west of the main Hawaiian Islands, is therefore outside the North American ECA. Vessels transiting the Papahānaumokuākea PSSA are not subject to North American ECA fuel-sulphur limits, although they remain subject to the global MARPOL Annex VI sulphur cap of 0.50 percent (effective 1 January 2020) and to any voluntary ECA-equivalent fuel use under shipowner low-sulphur policies.
The Hawaii exclusion has been cited in subsequent MEPC discussions as an example of the localised costs of ECA fuel supply for remote-island jurisdictions, and as a precedent for analogous ECA exclusions in other archipelagic settings. It distinguishes Papahānaumokuākea from PSSAs that fall within ECA boundaries, including the Baltic Sea PSSA (which falls within the Baltic SECA-NECA) and the Western European Waters PSSA (which falls within the North Sea SECA and the Mediterranean SECA from 2025).
Relationship to IMO Polar Code (geographic non-application)
The IMO Polar Code, adopted by Resolution MSC.385(94) and Resolution MEPC.264(68), applies to vessels operating in waters poleward of 60 degrees north or south (with specified exceptions), entering force on 1 January 2017. Papahānaumokuākea, lying between approximately 21 degrees and 28 degrees north latitude, is well below the 60 degrees north threshold and is therefore outside the geographical scope of the Polar Code. The Polar Code is referenced here only for completeness in the cross-pillar IMO special-area comparison; it has no application to vessels transiting the Northwestern Hawaiian Islands.
The cross-pillar IMO special-area architecture for Papahānaumokuākea consists of the PSSA designation under MEPC.171(57), the IMO ATBA and PSSAREP under SOLAS V/10 and V/11, the global MARPOL Annex VI sulphur cap, and the global MARPOL Annex I, II, III, IV and V discharge restrictions. The Polar Code, the Antarctic Special Area framework and the regional ECAs do not apply.
Trans-Pacific cargo lane: ~12,000 ships per year
The Northwestern Hawaiian Islands lie astride the great-circle Trans-Pacific shipping route between the United States West Coast (Long Beach, Oakland, Tacoma, Vancouver) and East Asia (Yokohama, Busan, Shanghai, Hong Kong, Singapore). The great-circle route from Los Angeles to Yokohama passes approximately 600 to 800 nautical miles north of the Hawaiian main islands, with several major service patterns crossing or skirting the Monument boundary. Approximately 12,000 ships per year transit the wider Northwestern Hawaiian Islands corridor on Trans-Pacific service, including container vessels of the principal alliances (2M, Ocean Alliance, THE Alliance), bulk carriers, tankers and vehicle carriers.
The 2008 PSSA ATBA established a clear routeing rule: vessels of 1,000 GT and above must remain outside the Monument boundary, requiring a typical course adjustment of 50 to 150 nautical miles north of the Monument. The post-2016 expansion of the boundary required updated chart corrections and AIS-based passage planning, with approximately 80 to 100 additional nautical miles of detour for vessels previously routing close to the original 2006 boundary. The marginal fuel cost of the post-2016 detour for a typical 14,000 TEU container vessel at 18 knots is approximately 30 to 60 metric tonnes of fuel oil per transit, or roughly 0.3 to 0.6 percent of voyage fuel consumption, an addition that has been absorbed into Trans-Pacific service economics without material impact on the principal trade lane.
The PSSA architecture has eliminated near-grounding incidents around the Northwestern Hawaiian Islands, with no documented post-2008 grounding of an ATBA-subject vessel within the Monument. The pre-PSSA period saw several grounding incidents, including the 2005 grounding of the longliner Casitas at Pearl and Hermes Atoll (which contributed to the urgency of the Monument designation) and earlier 1990s longline-vessel groundings at French Frigate Shoals.
Hawaiian Islands cruise sector: ~50,000 pax annually
The Hawaiian Islands cruise sector serves the main inhabited Hawaiian Islands (Honolulu, Kahului, Hilo, Kona, Nawiliwili) on inter-island and Trans-Pacific itineraries operated by Norwegian Cruise Line (Pride of America, the only US-flag cruise vessel), Princess Cruises, Holland America, Royal Caribbean, Carnival and several luxury operators. Annual cruise passenger volume to Hawaii is approximately 50,000 pax specifically for Northwestern Hawaiian Islands-adjacent itineraries, with the wider main-island cruise sector serving approximately 350,000 to 400,000 pax annually.
The Northwestern Hawaiian Islands corridor is served by a small number of expedition-cruise operators offering Midway Atoll-focused itineraries, typically with 50 to 100 passengers per voyage, operating under specific Monument permits issued by USFWS for Midway access (the only emergent island in the Monument with visitor infrastructure). All cruise vessels above 1,000 GT are subject to the IMO ATBA and may not transit the Monument; cruise vessels visiting Midway under permit operate on a case-by-case authorisation outside the standard ATBA framework, with strict route, anchoring and discharge controls.
The cruise industry compliance pattern has been generally strong: the Cruise Lines International Association (CLIA) member-line policies all incorporate the Papahānaumokuākea ATBA into route planning, and the few documented incidents have involved smaller expedition operators rather than principal CLIA members. Post-2020 cruise resumption following the COVID-19 pandemic interruption restored Northwestern Hawaiian Islands expedition itineraries on a reduced footing, with the 2024 season approximately 60 percent of the 2019 baseline.
Post-2017 expansion AIS / chart implications
The 2016 boundary expansion to ~939,000 km² required updated nautical chart corrections, AIS routeing references and electronic navigation chart (ENC) overlays. The United States National Oceanic and Atmospheric Administration nautical-chart office and the United States Coast Guard issued the principal chart corrections through 2017, with the United States Coast Pilot Volume 7 updated in the 2017, 2018 and 2019 editions. The United Kingdom Hydrographic Office (UKHO) issued corresponding Notices to Mariners through Admiralty chart updates 2017 to 2018.
Electronic Chart Display and Information System (ECDIS) overlays were updated in the IMO S-57 and subsequent S-101 ENC standards, with the Monument boundary represented as both an “area-to-be-avoided” feature class and an “environmentally sensitive sea area” feature class. ECDIS audible alarms are configured by default to trigger on planned route intersection with either feature class, supporting passage-plan compliance.
Satellite AIS providers (exactEarth, Spire, ORBCOMM) added Papahānaumokuākea boundary polygons to their commercial-route compliance feeds in 2018, allowing Trans-Pacific shipowners to monitor fleet compliance in near-real-time. The Monument boundary is now reproduced in the principal commercial route-planning software including Wartsila Voyage, Storm Geo BVS, ABB Ability Marine Pilot and IBM MetOcean route advisories.
State of Hawaii Marine Life Conservation District network
The State of Hawaii operates a parallel network of Marine Life Conservation Districts (MLCDs) in state waters around the main Hawaiian Islands, administered by the Hawaii DLNR Division of Aquatic Resources. The MLCD network comprises 11 districts including Hanauma Bay (Oahu), Pupukea (Oahu), Waikiki (Oahu), Honolua-Mokuleia Bay (Maui), Molokini Shoal (Maui), Manele-Hulopoe (Lanai), Lapakahi (Hawaii), Waialea Bay (Hawaii), Old Kona Airport (Hawaii), Kealakekua Bay (Hawaii) and Wai Opae (Hawaii). MLCDs prohibit or restrict fishing, anchoring on coral and resource take, with violation subject to state penalties under HRS Chapter 188.
The MLCD network does not extend to the Northwestern Hawaiian Islands, which are federal waters and Monument managed. The State of Hawaii role in Papahānaumokuākea is limited to state waters around Nihoa (the south-easternmost Northwestern Hawaiian Island, where the 3-nm state water envelope falls within the Monument) and to broader inter-jurisdictional coordination through the Co-Trustee structure. The MLCDs and Papahānaumokuākea constitute together the State of Hawaii spatial conservation portfolio, with the MLCDs targeting recreational and inshore stressors and the Monument targeting offshore shipping and commercial-fishery stressors.
The MLCD framework is referenced here as the State of Hawaii context for Papahānaumokuākea governance. The Co-Trustee architecture means that the Hawaii DLNR brings to Papahānaumokuākea management the operational experience of administering the MLCD network, including enforcement, monitoring, public education and stakeholder engagement protocols.
Comparison with Galapagos PSSA
The Galapagos PSSA, designated by Resolution MEPC.135(53) in 2005, is the closest analogue to Papahānaumokuākea among the IMO PSSA portfolio. Both are isolated oceanic archipelagos of high endemism (the Galapagos with approximately 25 percent endemic marine species, Papahānaumokuākea with approximately 25 percent), both are UNESCO World Heritage sites (Galapagos inscribed 1978, expanded 2001; Papahānaumokuākea inscribed 2010), and both are governed by ATBA-based PSSA architecture with ship reporting and discharge restrictions.
The principal differences are scale, governance and ECA relationship. Galapagos covers approximately 138,000 km² versus Papahānaumokuākea’’s 939,000 km². Galapagos is governed by Ecuador through the Galapagos National Park Service under the Special Law for Galapagos (1998, revised 2015), with no indigenous co-trusteeship. Papahānaumokuākea is governed by a four-party Co-Trustee structure including the Office of Hawaiian Affairs as indigenous co-trustee, a unique arrangement absent from any other IMO PSSA.
Both PSSAs face similar shipping-vector risks (Trans-Pacific transit, fishing-vessel encroachment, anchor damage, invasive-species introduction) and both have responded through similar Associated Protective Measures (ATBA, ship reporting, anchoring restrictions, discharge prohibitions). The Galapagos archipelago serves as the doctrinal reference point for ATBA-based PSSA design for isolated oceanic ecosystems, and Papahānaumokuākea built on Galapagos precedent in its 2008 designation. The two PSSAs are the principal IMO oceanic-archipelago PSSAs, complementing the coastal-archipelago Tubbataha Reefs PSSA and the continental-shelf Great Barrier Reef PSSA.
Comparison with Tubbataha Reefs PSSA
The Tubbataha Reefs PSSA, designated by Resolution MEPC.294(71) in 2017, is the immediate Asia-Pacific predecessor of Papahānaumokuākea. Both are UNESCO World Heritage natural sites, both are governed by ATBA-based PSSA architecture, and both rely on coastal-state enforcement coordinated with hydrographic-office chart updates.
The principal differences are scale and threshold. Tubbataha covers approximately 97,000 hectares (970 km²) of core park, expanded to roughly 360,000 hectares (3,600 km²) of regulated maritime space, versus Papahānaumokuākea’’s 939,000 km², a factor of approximately 260. The Tubbataha ATBA threshold is 150 GT versus Papahānaumokuākea’’s 1,000 GT, reflecting the smaller-vessel fishing-pressure profile in the Sulu Sea versus the larger-vessel Trans-Pacific transit profile in the central North Pacific.
Governance differs accordingly. Tubbataha is administered by the Tubbataha Management Office (TMO) reporting to the Tubbataha Protected Area Management Board (TPAMB) chaired by the Philippine Department of Environment and Natural Resources, with operational ranger presence on the North Atoll. Papahānaumokuākea is administered by the four-party Co-Trustee structure with no permanent ranger presence on the Monument (other than the Midway Atoll USFWS station, which is the principal inhabited outpost), relying on satellite AIS, periodic Coast Guard patrols and remote enforcement.
Both PSSAs have demonstrated effective post-designation incident reduction, and both serve as international reference cases for ATBA-based PSSA design.
Comparison with Antarctic Special Area + Polar Code
The Antarctic Special Area framework covers waters south of 60 degrees south latitude under the MARPOL Annex I, II, IV and V Special Area designations and under the IMO Polar Code for vessels operating in polar waters. The Antarctic framework is geographically and instrumentally distinct from Papahānaumokuākea, but shares several architectural features.
Both Papahānaumokuākea and the Antarctic Special Area regime impose discharge prohibitions stricter than baseline MARPOL Annex IV and V, requiring vessels to retain wastes on board for shore disposal rather than relying on baseline MARPOL discharge thresholds. Both regimes incorporate anchoring restrictions to protect bottom habitats, with Papahānaumokuākea protecting reef coral and the Antarctic regime protecting benthic communities and ice. Both regimes are anchored on UNESCO or analogous international recognition of conservation value, with Papahānaumokuākea inscribed as World Heritage and the Antarctic regime governed under the Antarctic Treaty System.
The principal differences are jurisdiction and legal basis. Papahānaumokuākea is a single-state PSSA within United States EEZ, governed by United States federal law (Antiquities Act, National Marine Sanctuaries Act) and IMO PSSA architecture. The Antarctic Special Area regime is a multilateral arrangement under the Antarctic Treaty System and the IMO MARPOL and Polar Code instruments, with no single-state sovereignty and no exclusive economic zone. Papahānaumokuākea is a tropical reef and seabird ecosystem; the Antarctic regime governs polar pack-ice, ice-shelf and Southern Ocean pelagic ecosystems.
The two regimes are complementary anchors at the equatorial-tropical and polar extremes of the global IMO special-area architecture, with the temperate PSSAs (Wadden Sea, Western European Waters, Baltic Sea, Great Barrier Reef) and the tropical-reef PSSAs (Galapagos, Tubbataha, Papahānaumokuākea) filling the latitudinal middle.
2024 NOAA budget request for Papahānaumokuākea management
The fiscal year 2024 NOAA budget request, submitted to the United States Congress in March 2023, included approximately USD 7.8 million for Papahānaumokuākea Marine National Monument management, of which approximately USD 4.5 million was allocated to NOAA Office of National Marine Sanctuaries operations, USD 1.8 million to USFWS Hawaiian Islands National Wildlife Refuge operations, and the balance to research, education and community programmes. The request was approximately 12 percent above the FY 2023 enacted level, reflecting post-2017 expansion operational requirements and post-2020 climate-adaptation programme scaling.
Co-funding includes Hawaii state appropriations through DLNR, OHA cultural-programme funding, federal partner contributions through NMFS Pacific Islands Fisheries Science Center, and external research grants through NSF, NOAA Sea Grant, the Pew Charitable Trusts and several private philanthropies (the Marisla Foundation, the Schmidt Ocean Institute and the Packard Foundation). The fiscal year 2024 enacted appropriation was finalised in March 2024 at approximately USD 7.2 million, slightly below the request but above the FY 2023 level.
The budget supports approximately 35 to 40 federal staff across the four agencies, plus approximately 10 to 15 cultural-practitioner stipends through OHA and a network of seasonal and contract personnel for Midway Atoll operations, monitoring expeditions and research support. Operational platforms include the NOAA Ship Hi’‘ialakai (until decommissioning in 2019), the NOAA Ship Oscar Elton Sette, the NOAA Ship Rainier and chartered research vessels including the R/V Searcher and the R/V Imua.
Climate adaptation: coral bleaching, sea-temperature monitoring
The post-2020 climate-adaptation programme for Papahānaumokuākea responds to documented warming of central North Pacific surface waters, increased coral-bleaching frequency, and ocean acidification across the Monument. Sea surface temperature in the Monument has increased by approximately 0.8 to 1.0 degrees Celsius since 1980, tracking the broader Pacific Decadal Oscillation and underlying greenhouse-gas-driven warming.
Major coral bleaching events documented in the Monument include the 2014 to 2015 event (severe bleaching at French Frigate Shoals, Pearl and Hermes, Lisianski), the 2019 event (moderate bleaching across the central Monument) and the 2023 event (severe bleaching at Lisianski and Maro Reef). Recovery has varied, with several reefs showing partial recovery on a 2 to 4 year cycle and others showing sustained coral cover decline. NOAA Coral Reef Watch provides near-real-time bleaching-alert products for the Monument, integrated with on-site validation cruises every 18 to 24 months.
Ocean acidification monitoring is conducted through a Monument-network of carbonate chemistry stations at Midway, French Frigate Shoals and Maro Reef, with surface aragonite saturation declining at approximately 0.5 percent per year over the 2010 to 2024 baseline. The acidification trend affects coral calcification, deep-water Lophelia and bamboo coral skeletal integrity, and pteropod abundance in the open-water zone.
The climate-adaptation programme includes habitat-resilience planning (identifying climate-refuge zones at the cooler-water Lisianski and Pearl and Hermes), assisted-migration research for selected coral species in collaboration with the University of Hawaii, monk seal climate-shift monitoring, and Native Hawaiian-led traditional-knowledge integration on inter-decadal variability. The 2024 Monument Management Plan revision integrates climate-adaptation as a cross-cutting management dimension across all programme areas.
Capstone: the seven major IMO PSSAs covered in the encyclopedia
The Papahānaumokuākea PSSA is the seventh major PSSA covered in this encyclopedia, alongside the Great Barrier Reef PSSA (1990, MEPC.44(30)), the Wadden Sea PSSA (2002, MEPC.101(48)), the Western European Waters PSSA (2004, MEPC.121(52)), the Galapagos PSSA (2005, MEPC.135(53)), the Tubbataha Reefs PSSA (2017, MEPC.294(71)) and the Baltic Sea PSSA (2005, MEPC.136(53)). The seven articles together cover the substantive IMO PSSA portfolio addressing the principal global ecosystem types: continental-shelf reef (GBR), tidal-flat coastal (Wadden Sea), continental-margin (Western European Waters), tropical oceanic-archipelago (Galapagos and Papahānaumokuākea), tropical reef-archipelago (Tubbataha) and semi-enclosed temperate sea (Baltic).
Cross-pillar thematic linkages run through the seven PSSAs. ATBA-based protection is the dominant design pattern, with thresholds varying from 150 GT (Tubbataha) through 500 GT (Galapagos) to 1,000 GT (Papahānaumokuākea, Great Barrier Reef). Ship reporting under SOLAS V/11 is consistent across all seven, with names varying (REEFREP for GBR, GALAPAREP for Galapagos, PSSAREP for Papahānaumokuākea). Discharge prohibitions vary from baseline MARPOL Special Area to enhanced anti-fouling and ballast-water restrictions, with Papahānaumokuākea adopting the strictest regime among PSSAs. UNESCO World Heritage anchoring is present in five of the seven (GBR, Wadden Sea, Galapagos, Tubbataha, Papahānaumokuākea), establishing UNESCO inscription as a strong but not strictly necessary precursor to PSSA designation.
The encyclopedia capstone treatment of the seven major PSSAs equips practitioners, regulators and researchers with a unified reference for the IMO PSSA architecture as it stands in 2026, supporting passage planning, port-state outreach, regulatory comparison, environmental-impact analysis and academic research across the global PSSA portfolio.
Formula, assumptions, and limits
Formula
The headline quantitative parameters for Papahānaumokuākea PSSA design and traffic analysis can be summarised:
Derivation
The 939,000 km² area is derived from the post-2016 boundary spanning the United States Exclusive Economic Zone around the Northwestern Hawaiian Islands, computed as the union of 200-nm EEZ envelopes around each emergent island and seamount complex, minus internal overlaps. The 7,000 species inventory is derived from the NOAA-USFWS Monument biodiversity inventory aggregated from approximately 1,200 published taxonomic studies through 2023. The 25 percent endemism rate is the published rate for the Hawaiian archipelago, calibrated against comparable archipelago endemism rates in Galapagos (around 25 percent) and Easter Island (around 35 percent). The 12,000 ships per year traffic figure is derived from satellite AIS coverage of the wider Northwestern Hawaiian Islands transit corridor in the 2018 to 2023 baseline.
Assumptions
The 939,000 km² figure assumes the post-2016 boundary as the operational PSSA boundary, including the 2017 IMO administrative update; the original 2008 PSSA designation references the 2006 boundary of 360,000 km². The 7,000 species and 1,750 endemic-species figures reflect 2023 inventory state and are subject to revision as taxonomy continues. The 12,000 ships per year figure is an annual aggregate; instantaneous transit density varies seasonally with peak Trans-Pacific liner-service deployment in the May to October period. The ATBA threshold of 1,000 GT applies to vessels carrying any cargo; vessels below 1,000 GT including domestic Hawaiian and federal-permitted vessels are not subject to ATBA observance.
Worked example
For a 10,000 TEU container vessel transiting from Long Beach to Yokohama on a great-circle route, the standard pre-PSSA passage would have routed approximately 200 to 300 nm north of the main Hawaiian Islands. The post-2016 ATBA requires the route to skirt the Monument by at least the EEZ boundary, requiring an additional approximately 80 to 120 nm of detour. At a service speed of 21 knots and a fuel consumption of 100 metric tonnes per day, the additional 4 to 6 hours of transit translates to approximately 17 to 25 metric tonnes of fuel oil per voyage, or approximately 0.3 to 0.5 percent of total voyage fuel consumption. This is the marginal compliance cost absorbed into the Trans-Pacific service economics.
Edge cases and limits
Force majeure entries: vessels in distress, requiring shelter, or with crew or vessel safety concerns may enter the ATBA under the standard SOLAS V/10 force majeure exception, with subsequent reporting to USCG Sector Honolulu. Permitted research and cultural-practitioner vessels operate under bespoke permits from NOAA, USFWS or OHA outside the standard ATBA framework. Native Hawaiian voyaging canoes (Hōkūleʻa, Hikianalia) operate under cultural-practitioner authorisation. Domestic Hawaiian commercial fishing vessels above 1,000 GT are addressed through separate fisheries-management instruments (the Western Pacific Regional Fishery Management Council bottomfish and pelagic management plans) rather than through the PSSA ATBA, although they are subject to Monument prohibition on commercial fishing within the Monument boundary.
Regulatory basis
The PSSA designation is anchored on Resolution MEPC.171(57). The ATBA is anchored on SOLAS Regulation V/10 and the IMO Ships’’ Routeing publication. PSSAREP is anchored on SOLAS Regulation V/11 and IMO MSC.1/Circ.1224. Discharge prohibitions are anchored on Title 50 CFR Part 404 and the Monument Management Plan. The Monument designation rests on the Antiquities Act of 1906 (54 U.S.C. § 320301) as exercised through Proclamation 8031 (2006) and Proclamation 9478 (2016). UNESCO World Heritage status rests on the 1972 World Heritage Convention. Native Hawaiian co-trusteeship rests on Proclamation 9478 and the Office of Hawaiian Affairs enabling provisions in the Hawaii State Constitution Article XII.
Common errors
A frequent passage-planning error is treating the original 2006 boundary as the operational ATBA, omitting the post-2016 expansion; this can place vessels inside the post-2017 boundary while reading earlier chart editions. A second common error is treating Papahānaumokuākea as falling within the North American ECA, applying 0.10 percent sulphur fuel limits unnecessarily; the Hawaii exclusion means baseline 0.50 percent global sulphur cap applies. A third error is treating PSSAREP as an automatic AIS function rather than a separate report submission; PSSAREP is a SOLAS V/11 ship reporting message distinct from AIS broadcast.
See also
- Particularly Sensitive Sea Area: Galapagos
- Particularly Sensitive Sea Area: Tubbataha Reefs
- Particularly Sensitive Sea Area: Great Barrier Reef
- Particularly Sensitive Sea Area: Wadden Sea
- Particularly Sensitive Sea Area: Western European Waters
- Particularly Sensitive Sea Area: Baltic Sea
- North American ECA
- US Caribbean ECA
- Antarctic Special Area and Polar Code
- MARPOL Convention
- MARPOL Annex I oil pollution prevention
- MARPOL Annex VI
- Calculator catalogue
Related calculators
- GMDSS - Sea Area Coverage Check
- SOLAS IV/9 - Sea area A2
- SOLAS IV/8 - Sea area A1
- SOLAS IV/11 - Sea area A4
- SOLAS IV/10 - Sea area A3
- Sea Water Cooling Pump Capacity
- Waterplane Area - Simpson 5-Ordinate
- Waterplane Area Coefficient (Cwp)